From Phenomena to Chrono.

Alessandro
Tasora kindly allowed us to
"interview" him on the 2nd December
2002. This is the full transcript from the
conversation:

B: Alessandro, tell us
a little about yourself:

A: I work at the university as a researcher,
so I have time to develop software about
topics I like most (expecially for 3D graphics),
either at the university and at home.
I also teach mechanical design, robotics
and automation at the local university:
that's why I am interested in computer simulation
of physical phenomena. In fact I decided
that I would have developed my own simulation
code
instead of using third party software: that's
why I decided to develop Chrono.

B: You wrote a very sucessful
plugin for Real 3D v3 - called Phenomena.
Do you have any thoughts about releasing
it for v4 ?

A: I would like, but I have no time for
that project, even if the user were very
happy and the feedback was very positive.
Anyway I know that other plugin developers
are working on similar plugins, for v4.

B: What is Chrono ?

A: Chrono
is a plugin for multibody simulation. In
detail, it can simulate the behaviour of
mechanical systems of whatever kind.
For example, you can build a car, made of
articulated suspensions, springs, engines,
etc., then you turn on the engine and you
can drive it. Dynamical effects are computed
realistically, not mocked-up as in videogames.
You can use it also to simulate automatic
devices, robots, walking machines, skeletons
for character animation, etc.

B: Chrono has been your
development baby now for a number of years
- why does it take so long to develop ?
Did you set your goals too high to start
with ?

A: In fact Chrono
was almost complete more than one year ago,
but as time passed, the more I had to implement
new features (and this continuously postponed
the writing of the manual and the last refinements).
This month I decided to dive into the manual,
because too much people is asking it, so
I wrote 90% of the reference manual with
a new publishing tool. In fact one of the
major causes of delays of Chrono
was the fact that I was using word-processing
sw for manual & help files (now I use
the PdfLatex
compiler, which is hard to learn at the
beginnning but allow you to keep your documentation
updated with less efforts, since it makes
Pdf and hypertext at once).
If I had set a simplier goal, of course
I would have finished the developement way
before. Chrono
started as a tool for simple mechanism simulation,
but here at the university we are already
using it for complex design tasks, so it
often happens that some coworker of mine
asks new feature for some specific job,
etc.
By the way, implementing multibody simulation
code maybe one of the hardest tasks for
a scientist/programmer!

B: How is Chrono coming
along ? Any ideas on a release date as yet
?

A: Chrono
is enough usable for whatever 'average'
user of Realsoft,
since I made the interface of its tools
as intuitive as possible.
There are, anyway, many hi-end features
which I would like to document better, and
to make them more usable (for example the
tool which studies the working area of robots,
etc.)

B: Would development of
your plugins be easier if the RS community
helped ? (eg manuals / testing etc ?)

A: I guess that I could ask some help
in manual proofreading, since I'm writing
it very fast, without paying too attention
to the syntax...

B: I understand that you
use Chrono yourself for a number of real-world
applications - care to tell us about any
of those ?

A: Yes, the fact that we used Chrono in
many real world applications is the major
cause of delay, as I told you before, but
this also means that it works very well,
since the correctness and the power of its
simulation engine has been tested with engineering
applications.

Some examples:

we designed and built a robot prototype
(name: "Sloth") which is one
of the fastest pick-and-place robots ever
existed. Chrono allowed us to simulate
inertial effects, kinematics, working
area, optimizations, motor choice, etc.,
before the robot was built.

in the same way, we designed, builted
and tested an innovative pneumatic robot
(name: "Torx").

similarly, we are developing a 6-dof
parallel robot for fast milling, with
innovative kinematics.

we designed a prosthetic shoulder which
has two motorized degrees of freedom,
using an inverse Cardano joint. Here
we used Chrono to choose the best solution
among many ideas. A prototype has been
built.

we studied the effect of road unevenness
on bicycle ride, for a research on road
safety. This was a very complex set of
200+ simulations.

we are designing a car-simulator (suspended
on actuators like the Jumbo simulators)
and we are including the Chrono simulation
kernel into the real-time DirectX visualization,
for the virtual-reality display.

we are simulating a pneumatic hand,
and much more...

B: Who is Chrono aimed
at ? The casual user or the engineer / designer
looking for accurate data / output ?

A: When we started, we had a lower profile
in mind, but now we see that it is more
targeted to the high-end user. Expecially
because we are stressing the features which
allow the introduction of digital controls,
etc. to simulate PLC, robots, automatic
devices, AI.
A low cost version will be available anyway,
simply without data plotting features.

B: Do you have any ideas
for future plugins ?

A: Yes, of course. Since Chrono
become more and more serious, we see that
there's the opportunity to push it on the
mechanical-engineering market. To do this,
it would be better to have also another
plugin, which turns Realsoft
into a 3D-CAD modeler (with better support
of nurb trimming, variational and parametric
dimensioning, vectorial outline output).
That's why I am studying how to port OpenCascade
to Realsoft
with a new plugin (see www.OpenCascade.com
to see what I mean). This would be useful
for architects, not only for engineers and
designers... And OpenCascade
is open-source.

B: You know the team at
Realsoft fairly well by now - do they look
after you in terms of development / support
? Is there anything further you would want
from Realsoft ?